Motorcycles are widely used for transportation and recreation. Motorcycles are typically powered by a drive assembly including an engine for generating power and a transmission for adjusting torque and speed. In one well-known motorcycle, the drive assembly comprises a left side drive layout wherein the engine includes a crankshaft or output shaft substantially parallel to an input shaft of the transmission. Power from the engine is transmitted to the transmission with a primary belt or chain interconnecting the parallel output and input shafts of the engine and transmission, respectively. The well-known drive assembly additionally includes a primary drive housing for enclosing the primary belt or chain interconnecting the parallel output and input shafts.
Over time, this left side drive layout has become one of several characteristic features that motorcycle enthusiasts identify as representative of quality and craftsmanship. Maintaining these characteristic features in new motorcycle designs is desirable to preserve the heritage of this popular motorcycle design. However, in many cases, these characteristic features demanded by motorcycle enthusiasts present obstacles to further development of the motorcycle. Thus, the challenge posed by these obstacles has been to improve the performance of the motorcycle while maintaining the traditional visual aspects of the motorcycle.
In this well-known motorcycle drive assembly, the engine and the transmission are typically mounted together by means of generally flat horizontal cantilevered pads that overlap one another at a rear of the engine crankcase and at a front of the transmission case. The two horizontal pads are typically held together by two vertical screws. To maintain proper alignment between the engine and the transmission, the primary housing extends across and bolts to the left sides of both the engine crankcase and the transmission case.
The lubrication system of the drive assembly typically comprises an oil pan, an oil return hose and an oil intake hose. The oil pan acts as a reservoir and contains oil while the oil is de-aerated and cooled. To provide the drive assembly with a compact configuration, the oil pan can be mounted remote or separately from the engine adjacent and below the transmission case. Unfortunately, due to the oil pan's positioning adjacent to the transmission case, the lubrication system requires lengthy hoses extending from the oil reservoir to the engine for providing oil to, and receiving oil from, the engine. These lengthy hoses require critical space, are prone to failure, and can be aesthetically unattractive.